1. Field of the Invention
The invention relates to a drain and inspection manhole for liquid conduits, in particular waste water and/or storm water drains, comprising a manhole section, which has a central longitudinal axis, which is formed as a composite pipe having a smooth cylindrical internal pipe and a corrugated external pipe, which has at least one aperture in the external pipe and an aperture, flush therewith, in the internal pipe, and which is equipped with a connector which is disposed in the aligning apertures and joined to the composite pipe and which has a central axis. The invention further relates to a manhole section for such a drain and inspection manhole.
2. Background Art
A drain and inspection manhole of the generic type is known from prior public use. The manhole section is produced from a commercial composite pipe which comprises a smooth cylindrical internal pipe and a corrugated external pipe. Apertures are cut into this composite pipe, into which a connector is inserted from within and joined to the composite pipe by gluing. This drain and inspection manhole can be produced easily and at a low cost, but it can be made only of PVC (poly vinyl chloride), because the connectors and the internal pipe must be glued together on the latter's inside.
The 1.07.96.50 HT leaflet entitled "opti-dran-System" of the company of Frarkische Rohrwerke Gebr. Kirchner GmbH+Co teaches a drain and inspection manhole, the manhole section of which consists of a simple corrugated pipe of PVC-U with connections injection-molded thereon at given distances. Apertures are cut into these connections, into which connectors are inserted from within, which are joined thereto by gluing or welding. A drawback of this known solution resides in that the drain and inspection manhole is rather difficult to clean because of the internal corrugation of the manhole section. The manhole is not very solid, because it is axially deformable.
EP 0 358 857 B1 teaches a drain and inspection manhole, the manhole section of which consists of a simple corrugated pipe which is closed at its root by a bottom of special design.